The biology of anopheline mosquitoes is being studied in relation to the capacity of these vectors to transmit malaria. Genetic, molecular, biochemical, and immunological studies are seeking to describe mechanisms in the mosquito that enhance or retard development of the malaria parasite with emphasis on the behavior of ookinetes, oocysts, and sporozoites. To facilitate these studies: 1) methods are being improved for cloning and transposing genes into mosquito germ lines, and 2) systems are being evaluated for the cryopreservation of mosquito embryos to increase our capacity to store genetic material. The ability to identify, clone, and transpose genes that regulate mechanisms that render mosquitoes refractory to parasite development should facilitate development of control strategies based on the introduction into the field of mosquito populations incapable of transmitting malaria.